diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
index 461e47c8e956..4532973f0dd4 100644
--- a/net/ipv6/ip6mr.c
+++ b/net/ipv6/ip6mr.c
@@ -2104,8 +2104,9 @@ static int __ip6mr_fill_mroute(struct mr6_table *mrt, struct sk_buff *skb,
 	if (c->mf6c_parent >= MAXMIFS)
 		return -ENOENT;
 
-	if (MIF_EXISTS(mrt, c->mf6c_parent))
-		RTA_PUT(skb, RTA_IIF, 4, &mrt->vif6_table[c->mf6c_parent].dev->ifindex);
+	if (MIF_EXISTS(mrt, c->mf6c_parent) &&
+	    nla_put_u32(skb, RTA_IIF, mrt->vif6_table[c->mf6c_parent].dev->ifindex) < 0)
+		return -EMSGSIZE;
 
 	mp_head = (struct rtattr *)skb_put(skb, RTA_LENGTH(0));